Scientists now believe cat litter was not the only material responsible for an underground nuclear-waste leak, the Santa Fe New Mexican reports.

A lead-tainted glove, as well as additional metallic and acidic materials, are other potential contributors to a thermal reaction hypothesized to have ruptured a container at the Waste Isolation Pilot Plant in New Mexico, the newspaper reported on Wednesday. Investigators have spent months looking into the February leak, which contaminated nearly two dozen workers and halted underground operations at the facility near Carlsbad.

Experts hit a dead end when they tried to create a heat reaction with just nitrate salts and organic cat litter, which Los Alamos National Laboratory had recently adopted as a packing material.

"But when you begin to add these very specialized conditions -- a little bit of acid, some of these trace metals -- the picture changes," said Nan Sauer, the Los Alamos Laboratory's associate director for chemistry, life and earth sciences.

The materials suspected to have caused the rupture were specific to the waste barrel that broke open, Sauer said. Fears that cat litter was the primary culprit previously sparked worries that hundreds of additional containers were in possible danger of bursting.

Still, the leak has prompted Los Alamos officials to revisit their procedures for handling leftovers from years of nuclear-arms work, Sauer told the New Mexico Legislature's Radioactive and Hazardous Materials Committee.

"Did our workers have adequate information to do the work that they needed to do?" she asked. "Did we look at all the nuances associated with the remediation of this waste so that we were sure that we were compliant?"